An AC/DC power converter is used to drive a string of LEDs. The AC/DC power converter includes a rectifier circuit for rectifying an AC input voltage into a DC voltage. The isolated AC/DC power converters additionally include a transformer to isolate the output (secondary side) from the input (primary side) of the converter and therefore separate grounds are used for the input and the output of the power converter circuit. The AC/DC power converters include PFC circuitry included in the controller that controls the flow of the input current so that the input current waveform is in phase with the waveform of the AC input voltage (e.g., a sine wave). For a good power factor, the input current waveform will follow the shape and phase of the input voltage.
When a fault is detected in a power converter, many controllers of power converters implement latched fault protection by stopping the controller and waiting for a manual startup of the controller and the power converter. A number of other controllers in response to a fault implement auto retry protection and automatically restart the controller and the power converter. Some power converters implement a selectable fault protection mode by adding an extra input pin. Based on the voltage applied to the extra pin, in response to a fault the controller of the power converter either selects latched fault protection or auto retry protection.